Following general anesthesia, a median cervicotomy was performed to obtain access to jugular vessels in 13 pigs (44.5 kg). A 24-French sheath was surgically inserted into the right external jugular vein (24); 6-French sheaths were placed into the left external jugular vein, left internal jugular vein, and right common carotid artery, respectively. Following intravenous administration of 5000 units of unfractionated heparin, 5-French pigtail catheters were advanced over a J-tipped 0.035-inch guide wire (Emerald, Cordis, Miami, FL) into the ascending aorta and superior vena cava. Two porcine 4-day old thrombi, 5-6 cm in length and 1-2 cm in diameter, were injected with 20 ml saline solution through the 24-French sheath using a tapered adapter 24. The tapered adapter allowed intact injection of thrombi through the sheath. A third thrombus was injected in 4 animals because the mean aortic pressure remained > 70 mm Hg or the mean pulmonary artery pressure remained < 25 mm Hg after injection of 2 thrombi. Total injected thrombus weight was 17.4 g. Of the 13 pigs, 3 died immediately after thrombus injection due to cardiogenic shock. Ten pigs developed cardiogenic shock but nevertheless survived; two required intravenous epinephrine (bolus of 1 mg) for profound systemic arterial hypotension following thrombus injection.